1. Field of the Invention
The present invention relates to a vibration motor suitable for mounting on a printed circuit board by reflow soldering.
2. Description of the Related Art
As a vibration motor of a structure suitable for surface mounting on a printed circuit board, as disclosed in Japanese Patent Publication (A) No. 11-234943, there is known one having a motor body with an eccentric weight attached to one end of a motor shaft, a metal holder frame provided with a pair of sandwiching pieces for fitting a motor case of the motor body from its upper portion and holding that motor case, and a pair of external terminal pieces attached to a plastic end cap for closing an opening of the motor case at the side opposite to the eccentric weight, wherein the flat back surface of the metal holder frame and a pair of external terminal pieces are adhered to bonding patterns and a pair of power feed patterns by coating cream solder and are fixed by reflow soldering.
However, the above vibration motor has had the following problems.
Since the motor case is fitted by an elastic force derived by the pair of the sandwiching pieces which are open at their upper side, the motor case tends to be unfastened from the sandwiching pieces or the sandwiching force tends to be loosened when a mobile phone, which mounts the vibration motor with the heavy eccentric weight, receives a shock when it is fallen or the like. Therefore, the prior-art vibration motor has a disadvantage of low reliability against shock. In addition, the flat back surface of the metal holder frame is provided with a bottom-up recess portion for pooling solder so that the motor case must have flat sides in order to stably fit the motor case, which is held by the pair of the sandwiching pieces, against the bottom up surface of the bottom-up recess portion. Therefore, the vibration motor has a structure not suitable for the use of a motor case with a round circumferential surface.